Recall the formula for the perimeter (circumference) of a circle.
This mathematics problem involves applying core mathematical principles and formulas. Below you will find a complete step-by-step solution with detailed explanations for each step, helping you understand not just the answer but the method behind it.
ScanSolve AI Answer
Step 1: Recall the formula for the perimeter (circumference) of a circle.
The circumference $C$ of a circle is given by the formula:
$$C = \pi d$$
where $d$ is the diameter of the circle.
Step 2: Substitute the given diameter into the formula.
The diameter $d = 21 \text{ cm}$. We will use the approximation $\pi = \frac{22}{7}$.
$$C = \frac{22}{7} \times 21 \text{ cm}$$
Step 3: Calculate the circumference.
$$C = 22 \times \frac{21}{7} \text{ cm}$$
$$C = 22 \times 3 \text{ cm}$$
$$C = 66 \text{ cm}$$
The perimeter of the circle is $\boxed{\text{66 cm}}$.
